Cold forming of articles



Oct. 22, 1968 WMV auf l l A slm 44% 26 lll-gu`\ Oct. 22, 1968 F. J. FUCHS, JR 3,406,555

`COLD FORMING OF ARTICLES Filed April 5, 1966 2 Sheets-Sheet 2 United States Patent O 3,406,555 COLD FORMING F ARTICLES Francis Joseph Fuchs, Jr., Princeton Junction, NJ., as-

signor to Western Electric Company, Incorporated, New York, N .Y., a corporation of New York Filed Apr. 5, 1966, Ser. No. 540,382 6 Claims. (Cl. 72--377) ABSTRACT 0F THE DISCLOSURE An article is cold formed from a single length of material which increases in ductility when hydrostatic pressure is 'built up therein, the length of material is subjected to forces sufficiently great to build up hydrostatic pressure in the material, so as to increase the ductility thereof, and a forming member is advanced into engagement with at least a portion of the material, while the material is in the state of increased ductility, to shape the portion into an irregular configuration.

This invention relates to cold forming of articles, and more particularly to methods of cold forming of articles from metal stock in a single operation wherein the articles are characterized by having a shank portion and at least one section of an irregular configuration.

As used hereafter in the specification, the term irregular configuration is to be construed broadly. This term includes, among others, those cases wherein the section of the article having the irregular configuration has (l) a cross-section different from that of the shank with its central axis either coincident or non-coincident with that of the shank (for example, 'see FIGS. 8, 9B and 9C); or (2) a cross-section identical to that of the shank with its central axis either coincident or non-coincident (for example, see FIG. 9A) with that of the shank. In the cases mentioned above, the cross-section may be either uniform or non-uniform.

In the manufacture of a class of articles, characterized by having a shank and an end section of a complex or highly irregular configuration (for example, see FIGS. 7D and 8), by presently known methods, two lengths of stock are individually forged to the respective configurations of the shank and the end section. Thereafter the shank and end section are joined together by welding, soldering, or the like. This multi-operation process requires several pieces of apparatus, is time consuming and expensive, in addition to producing scrap. The time consumed and expense involved are compounded when it is desired to manufacture articles having irregularly configurated sections on both ends of a shank (see FIG. 9B), or articles having an irregularly configurate'd Section intermediate two shank portions (see FIG. 9C).

The present invention provides novel methods of cold forming, from a single length of metal stock in a single operation, articles of a class characterized by having a shank and at least one section having an irregular configuration. These methods are to be distinguished from presently known processes such as the conventional cold heading technique, or compression of a length of uniform bar stock to form the head of an article, or other like techniques.

Accordingly, an object of this invention is to provide new and improved methods of cold forming of articles.

Another object is to provide new and improved methods of cold forming of articles from metal stock in a single operation, wherein the articles are characterized by having a shank portion and at least one section having an irregular configuration.

Another object is to provide new and improved methods of cold forming of articles from a single length of stock in a single step operation, wherein hydrostatic pressure is "ice built up in a length of stock prior to shaping a section of the length to an irregular configuration.

With these and other objects in view, and in accordance with a method of cold forming of articles illustrating certain principles of the invention, a length of metal is placed in axial compression such that hydrostatic pressure is built vup in it. Thereafter, at least one section of the length is shaped to an irregular configuration. In a specific embodiment of the method of the invention, after hydrostatic pressure has Vbeen built up in the length, a

shaping die is applied transverselyv of the longitudinal axis of the length to shape a section of it to an irregular configuration.

Other objects and advantages of the invention will become apparent by reference to the following detailed vspecification and accompanying drawings, wherein:

FIG. 1 is a schematic diagram, mostly in cross-section, of an apparatus which may 'be used in the practice of the method of the invention, and shows a length of metal stock located in a lower die assembly of the apparatus;

FIG. 1A. is a schematic diagram, mostly in cross-section, of an alternative arrangement of the lower portion of the apparatus shown in FIG. 1;

FIGS. 2 and 3 show the apparatus of FIG. 1 in various stages of its operation;

FIG. 4 is a View taken along line 4-4 of FIG. 2 and shows the arrangement of ydies in the lower die assembly;

FIG. 5 is a view taken along line 5-5 of, FIG. 2 and shows the transverse configuration of a die cavity contained in an upper die assembly of the apparatus;

FIG. 6 is a view taken along line 6 6 of FIG. 2 and shows the cross-sectional configuration of a tool mounted for movement within the upper die assembly;

FIGS. 7A-71D are a series of views Idepicting the changes in the configuration of a length of metal stock as it is cold formed into a finished article in accordance with the principles of the method of the invention;

FIG. 8 is a perspective view of the finished article shown in FIG. 7D; and

FIGS. 9A-9C illustratively depict some irregular configurations of sections which may be formed on Shanks from lengths of metal stock in accordance with the principles of the invention.

General description Referring to lFIG. 8, there is shown a relay core 10 comprised of an elongated shank 11 and an end section 12 having a complex or Ihighly irregular configuration. Relay core 10 belongs to that class of articles characterized by having a shank and at least one section of an irregular configuration. Shank 11 is of substantially uniform circular cross-section (although it need not be), except for a flat 16, projections 17, and knurls 18, formed thereon.

Section 12 has a :substantially `different configuration than that of shank 11; that is, section 12 has a flat surface 21 parallel to the central axis of shank 11 and a pair of substantially fiat side walls 20 converging in a rounded vertex. .End section 12 terminates in a flat end sur-face 22. The cross-section of end Isection 12 is uniform and is symmetrical about an imaginary central axis, which is not coincident with the central taxis of shank 11.

Relay core 10 is presently manufactured by first forging fiat 16, projections 17, and knurls 18 on a first length of metal stock, and then forging a second length of stock into the complex configuration of end section 12. Thereafter, shank 11 and section 12 fare welded together. As discussed supra, such za multi-step method of manufacturing relay cores 10 is time consuming and expensive, and produces scrap.

In FIG. 1 there is schematically shown an apparatus which lmay be used in the practice of the method of the invention to form a relay core 10 from a length of met-al 3 stock 19 (FIG. 7A) in a single operation. The apparatus comprises Ean upper assemlbly 23 movable relative to a lower assembly 24 which is mounted on a stationary support 26.

Lower assembly 24 includes a lower die assembly 31 which comprises five or other suitable number of die segments 32 (FIG. 4) mounted in a cavity 33 of lower housing 34. One of the die segments, segment 32a, has an appropriate die face 35 for forming at 16 Iand projections 17 on shank 11. All of the die segments 32 have appropriate die faces for forming knurls 18. Die segments 32 and cavity 33 have complementary tapers, which coact to urge die segments 32 inwardly when die assembly 31 is moved downwardly into cavity 33. Die segments 32 are held together by a resilient retaining band 36. A springloaded positioner rod 37 is mounted on support 26 and functions to locate length 19 when it is inserted into die assembly 31.

Upper assembly 23 includes an upper die assembly 41 mounted in a cavity of an upper housing 43. Die assembly 41 comprises two segments 44 which are held together by a resilient :retaining Iband 45. Die segments 44 and cavity 42 have complementary tapers. The die faces of die segments 44 dene an elongated chamber 46 (FIG. 5) having a cross-section corresponding to that of section 12 of relay core 10. A tool 48, having a cross-section (FIG. 6)

` corresponding to that of chamber 46, is mounted on a ram 47 for close-fitting movement therein.

A locating pin 49 is mounted on upper housing 43 opposite a locating hole 51 formed in lower housing 34. A shaping die 56 is 4mounted in the lower end of upper housing 43 transverse to the central axis of chamber 46. Shaping die 56 has a die lface 57 having a configuration corresponding to at portion 21 of section 12 of relay core 10. The portion of chamber 46 opposite shaping die 56 delines a female die cavity 59.

Practice of the method A predetermined length 19 (FIGS. 1 and 7A) of metal stock is placed into the opening defined by die faces of die segments 32. Length 19 comes to rest on positioner rod 37 and is maintained thereby in a predetermined position (FIG. l) relative to the die faces of die segments 32.

With reference to lFIG. 2, a press, or other suitable force applying mechanism (indicated schematically by arrows 61), is actuated to drive upper housing 43 and dies 44 and 56 downwardly. As upper housing 43 descends, the upper end of length 19 enters die cavity 59 and chamber 46 (shaping ldie 56 being slightly retracted at this time), and locating pin 49 enters locating hole 51 (FIG. l). As upper housing 43 continues to descend, it contacts and forces die segments 32 downwardly into cavity 33 until upper housing 43 contacts lower housing 34. During the downward movement of housing 43, the die faces of die segments 32 squeeze length 19 to -form Hat 16, projections 17, and knurls 18 (FIG. 7B).

During the forcing of die segments 32 into cavity 33, the metal, displaced by the squeezing of the lower portion of length 19 to form at 16 and projections 17, is forced to flow outwardly against positioner rod 37. At this point, shank 11 is fully formed, and the entire length thereof is rigidly confined by die segments 32.

With reference to FIG. 3, ram 47 and tool 48 are now advanced downwardly, -by another press (indicated schematically lby arrow 62), to place length 19 in axial compression. As tool 48 continues to be advanced, suliicient compressive forces are applied by tool 48 to build up suficient hydrostatic pressure in length 19 to greatly increase the ductility of the lmetal of length 19. With continued advancement of tool 48, the metal of the upper portion of length 19 begins to flow into die cavity 59. Length 19 is placed in hydrostatic pressure since its length is confined by die segments 44 and 32 (except opposite shaping die 56) to exert radial forces while compressive forces are applied by tool 48. Figuratively described, the upper prtion of length 19 begins to fatten (FIG. 7C).

Hydrostatic pressure is a term used in the art to describe that condition where sufficient external uniform pressure is applied to a piece of metal, whether relatively soft or relatively hard, such that the ductility thereof is increased. For a further discussion of hydrostatic pressure relative to metals and other materials which exhibit an increase in ductility when in hydrostatic pressure, see Large Plastic Flow and Fracture, Dr. Percy Bridgman, 1952, McGraw-Hill Book Company.

When ram 47 has reached its lower limit of downward movement (as determined by a shoulder 63 of ram 47 abutting dies 44), the end of tool 48 is laterally aligned with the top of shaping die 56 to close off chamber 46 and define die cavity 59 (FIG. 3). Shaping die 56 is now moved inwardly by a hydraulic or other suitable mechanism (indicated schematically by arrow 64) with sutlicient force such that its die face 57 forces the metal (which is in hydrostatic pressure) into cavity 59 to assume the shape of complexly coniigurated section 12 (FIGS. 7D and 8).

It is to be understood that the formation of hat 16, projections 17 and knurls 18, are not essential steps in the practice of the method, and are described for the purpose of illustrating some details which may be formed on a length of bar stock. The principal feature of this invention, as discussed supra, is the formation of an irregularly configurated section, such as end section 12, on a shank from a single length of metal stock in a single step operation.

The method, as described above, is suitable for cold forming of articles from lengths 19 of relatively soft metals, for example copper or low carbon steel, among others. However, the method may be practiced to cold form relatively hard materials, for example high carbon steel or molybdenum, among others. In either case, sufficient compressive forces must be exerted on length 19, while confining it with die segments 32 and 44, to build up suicient hydrostatic pressure therein to increase its ductility. In cold forming a length 19 of hard metal into a relay core 10, axial compressive forces of suticient magnitude are applied to both ends of length 19 to build up hydrostatic pressure therein, such that the brittle-toductile transition phase occurs. Simultaneously, die assembly 31 is driven downwardly such that die face 35 of die segment 32a forces the metal to ow out ofthe bottom of die assembly 31 during the formation of at 16 and projection 17.

The lower portion of the apparatus shown in FIG. l may be modified to that shown in FIG. 1A, when a length 19 of hard metal is to be cold formed into a relay core 10. A ram 66, having a tool 67 mounted thereon, replaces positioner rod 37. Ram 66 drives tool 67 to apply compressive forces to the bottom of length 19 simultaneously as ram 47 drives tool 48 to apply compressive forces to the top thereof, to bulid up hydrostatic pressure in the length. Substantially at the same time, die assembly 31 is driven downwardly into housing 34 so that length 19 is rigidly confined by die segments 32 and 44. As die segments 32 approach the bottom of the cavity, ram 66 is backed ot slightly to permit the metal displaced by die segment 32a to ow towards the bottom of die assembly 31, while maintaining the length 19 in axial compression.

Appropriate controls, which are known to those skilled in the art, may be associated with the illustrative apparatus shown in FIGS. 1 and 1A to control the sequence of operations of the various parts respectively, as described supra.

Although the method of the invention has been described as a series of incremental steps, as illustrated by FIGS. 7A-7D, relay cores 10 have been formed from single lengths 19 of copper and low carbon steel in single operations in a relatively short time on the order of a few seconds each. Using an apparatus similar toV that schematically shown in FIG. l, lengths 19 were subjected to approximately 400,000 p.s.i. while being confined by die segments 32 and 44 to build up hydrostatic pressure therein.

From the foregoing, it will be appreciated that this method, as applied to the manufacture of relay cores 10, is economically attractive as compared with the present technique of making them, because of the relatively short recycling time, relatively small investment needed for the relatively simple apparatus to practice it, and the elimination of scrap. Also, relay cores manufactured in accordance with the subject method are at least as strong as those manufactured in accordance with present techniques.

It will also be appreciated that either relatively soft or relatively hard metals can be employed as metal stock from which to form articles of the class characterized as having a shank portion and at least one section of an irregular configuration, in accordance with the method of the subject invention. It will further be appreciated that the irregularly configurated section can be formed anywhere along the length of the stock, for example, on one end (FIGS. 8 and 9A), at a preselected position between the ends thereof (FIGS. 9C), or on both ends thereof (FIG. 9B).

Referring to FIGS. 9B and 9C, irregularly configurated section 12 has a flat surface formed by die face 57 of shaping die 56. However, die face 57 may have any shape desired, for example, it may be curved, notched, or the like. Also, in FIGS. 9B and 9C, section 12 is uniform and substantially symmetrical about an imaginary central axis which is not coincident with the central axis of shank 11, although it may be coincident if desired. In FIG. 9A, section 12 has the same cross-sectional configuration (round) as that of shank 11, but it has a larger diameter and its central axis is not coincident with that of the shank, although it may be coincident if desired. Although not shown, it is apparent that section 12 may be a square formed on a round shank or a round cylinder formed on a square shank, or have a longitudinal taper, or the like. In fact, there is literally no limitation on the configuration into which section 12 may be formed, if it is shaped while the metal of the length of stock is placed in hydrostatic pressure in accordance with the principles of this invention. Conversely, if the metal is not so placed in hydrostatic pressure, the configuration into which section 12 may be formed is severely limited.

It is to be understood that the above-described embodiments are merely illustrative of the principles of the method of the invention, and other embodiments thereof may be devised without departing from the scope of the invention.

What is claimed is:

1. A method of cold forming an article from a length of metal, comprising the steps of:

confining a length of metal;

applying axial compressive forces to the length of metal while it is confined to build up hydrostatic pressure therein, such that the ductility of the metal is increased; and

shaping at least one section of the metal, while it is in hydrostatic pressure, by punching the length of metal with a shaping die applied thereto in a direction transverse of the central axis thereof to shape it to an irregular configuration.

2. The method of cold forming an article according to claim 1, wherein the length of metal is of relatively -hard metal and is subjected to compressive forces sufficient in magnitude such that it undergoes a brittle-toductile transition prior to being shaped.

3. A method of cold forming a relay core from a single length of metal bar stock of uniform cross-section, the relay core having a shank and an end section of an irregular configuration substantially as shown in FIG. 8, comprising the steps of:

placing a first portion of a length of stock into a lower 6 die assembly such that the first portion is rigidly confined thereby;

advancing an upper die assembly onto the remaining portion of the length such that the end thereof passes through and out of a die cavity contained in the upper die assembly, the die cavity having a configuration corresponding to the end section of a relay core to be cold formed;

applying a tool to the end of the remaining portion,

the tool exerting axial compressive forces of a sufficient magnitude to build up suflicient hydrostatic pressure in the length so that the ductility thereof is increased and the portion of the length extending out of the die cavity fiows into it; and

moving a shaping die, from a direction transverse of the central axis of the length, into the die cavity to shape the metal therein to the irregular configuration.

4. A method of cold forming a relay core according to claim 3, further comprising the step of:

simultaneously applying another tool to the end of the first portion of the length While it is rigidly held in the lower die assembly, this tool exerting axial compressive forces of a sufficient magnitude to assist the first tool in 'building up hydrostatic pressure in the length.

5. The method of cold forming an article from a length of material which increases in ductility when subjected to sufhciently high compressive forces, comprising the steps of:

confining said length of material;

applying axial compressive forces to said confined length of material sufficiently great to cause said material to increase in ductility; and

advancing a forming member in a direction transverse of the central axis of the length of material and into engagement with at least a portion of said material, While said material is in said state of increased ductility, to shape said portion into an irregular configuration.

6. A method of cold forming an article from a single length of metal bar stock of uniform cross-section, the article having a shank and at least one section of irregular configuration, comprising the steps of placing said first portion of said length of stack into a lower die assembly such that the first portion is rigidly confined thereby;

advancing an upper die assembly onto the remaining portion of the length such that the end thereof passes through and out of a die cavity contained in the upper die assembly, the die cavity having a configuration corresponding to the section of irregular configuration to be cold formed;

applying a tool to the end of said remaining portion with such force las to build up hydrostatic pressure in said length so that the ductility thereof is increased, and to cause the portion of the length extending out of said die cavity in said upper die assembly to fiow thereinto; and

moving a shaping die, from a direction transverse of the central axis of said length, into said die cavity m said upper assembly, to shape the metal therein to said irregular configuration.

References Cited UNITED STATES PATENTS 1,971,548 8/1934 Wilcox 10-78 2,513,710 7/1950 Brauchler 72-353 3,120,769 2/ 1964 Hatebur 10-78 3,286,498 11/1966 Cogan 72-356 CHARLES W. LANHAM, Primary Examiner.

L. A. LARSON, Assistant Examiner. 

